Steam generator

ABSTRACT

A steam generator includes: an annular member ( 21 ) that surrounds a U-bent portion ( 18 ) obtained by collectively disposing bent portions of a plurality of heat transfer tubes and is provided between an outer peripheral portion of the U-bent portion ( 18 ) and a tube bundle shroud ( 3 ) surrounding the outer peripheral portion so as to have a predetermined gap with respect to the U-bent portion ( 18 ); a second support member ( 22 ) that is provided between the annular member ( 21 ) and the tube bundle shroud ( 3 ); and a third support member ( 23 ) that is attached to a cylinder portion ( 2 ) accommodating a plurality of heat transfer tubes and supports the second support member ( 22 ).

FIELD

The present invention relates to a steam generator with a U-bent portion obtained by collectively disposing bent portions of a plurality of heat transfer tubes.

BACKGROUND

A steam generator includes a U-bent portion in which a plurality of heat transfer tubes with U-shaped bent portions are collectively disposed so as to form a semi-spherical shape on the whole. There is known a structure which improves the resistance (quake resistance) of the U-bent portion with respect to an earthquake. For example, Patent Literature 1 discloses a structure in which a support member fixes a member that holds a plurality of heat transfer tubes of a U-bent portion. Further, Patent Literature 2 discloses a structure in which heat transfer tubes of a U-bent portion are fixed to a container (cylinder portion) of a steam generator through a support member.

CITATION LIST Patent Literature

-   Patent Literature 1: U.S. Pat. No. 6,772,832 -   Patent Literature 2: U.S. Pat. No. 5,692,557

SUMMARY Technical Problem

The technique of Patent Literature 1 has a structure in which the support member fixes the member that holds the plurality of heat transfer tubes of the U-bent portion. However, since the support member is not fixed to the container of the steam generator, there is a concern that the quake resistance of the U-bent portion may not be sufficiently ensured. The technique of Patent Literature 2 has a structure in which the heat transfer tubes are fixed to the container of the steam generator through the support member. However, when a restraining force of the U-bent portion is large, there is a concern that the resistance with respect to flow oscillation may be influenced.

Here, when an earthquake acceleration generated in the event of an earthquake is applied in the in-plane direction of the heat transfer tube, that is, the direction following a plane including the bent portion of the heat transfer tube, the U-bent portion may withstand the earthquake acceleration by the rigidity of the heat transfer tube. Meanwhile, when the earthquake acceleration is applied in the out-of-plane direction of the heat transfer tube, that is, the direction perpendicular to the plane including the bent portion of the heat transfer tube, there is a problem in which the U-bent portion is largely displaced due to the to rigidity of the heat transfer tube in the direction. Further, in the techniques of Patent Literatures 1 and 2, the support member immovably fixes the U-bent portion. For this reason, the restraining force of the U-bent portion excessively increases, and hence there is a concern that the resistance with respect to the flow oscillation may be influenced.

It is an object of the invention to ensure the quake resistance and the resistance with respect to the flow oscillation in the U-bent portion.

Solution to Problem

According to an aspect of the present invention, a steam generator includes: a first support member that surrounds a U-bent portion obtained by collectively disposing bent portions of a plurality of heat transfer tubes and is provided between the U-bent portion and a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion so as to have a predetermined gap with respect to the U-bent portion; a second support member that is provided between the first support member and the tube bundle shroud; and a third support member that is attached to a cylinder portion accommodating the plurality of heat transfer tubes and supports the second support member.

In the steam generator, when the U-bent portion is vibrated in a direction parallel to the radial direction of the cylinder portion having a circular cross-section due to an earthquake or the like, the vibration of the U-bent portion may be received by the cylinder portion through the first support member, the second support member, and the third support member, and hence the quake resistance of the U-bent portion is ensured. Further, since the first support member is disposed with a predetermined gap with respect to the U-bent portion, the restraining force of the U-bent portion may be reduced. For this reason, since the vibration abrasion or the like of the heat transfer tube caused by secondary cooling water passing between the first support member and the U-bent portion may be suppressed during the operation of the steam generator, the above-described resistance may be ensured by reducing an influence on the resistance with respect to the flow oscillation of the heat transfer tube.

Advantageously, in the steam generator, the first support member includes a regulation member that sandwiches a bridge, connecting a plurality of holding members connecting ends of a plurality of vibration preventing members disposed between the heat transfer tubes in the U-bent portion, with a predetermined gap therebetween so as to regulate a movement of the bridge. The regulation member attached to the first support member does not restrain the heat transfer tube which is supported by the bridge through the vibration preventing member and the holding member in the U-bent portion. For this reason, since the vibration abrasion or the like of the bridge caused by the secondary cooling water passing through a gap formed between the regulation member and the U-bent portion may be suppressed during the operation of the steam generator, the above-described resistance may be suppressed by reducing an influence on the resistance with respect to the flow oscillation of the heat transfer tube. Further, when the U-bent portion and the bridge are vibrated by an earthquake or the like, the regulation member which is supported by the cylinder portion through the first support member, the second support member, and the third support member regulates the vibration of the bridge. Since the gap between the regulation member and the bridge is smaller than the gap between the first support member and each of the plurality of heat transfer tubes of the U-bent portion, the vibration of the U-bent portion may be further effectively suppressed. As a result, it is possible to further reliably ensure the quake resistance of the U-bent portion by using the regulation member.

According to a third aspect of the invention, in the second invention, the regulation member may have an orifice that is formed at a portion facing the bridge. In this way, since it is possible to obtain a damping action that damps the vibration of the bridge, it is possible to alleviate an abrupt change in the acceleration acting on the plurality of heat transfer tubes of the U-bent portion, and hence to further improve the quake resistance of the U-bent portion.

Advantageously, in the steam generator, a plurality of the second support members extend radially from the first support member toward the tube bundle shroud and are fixed to the tube bundle shroud, and a plurality of the third support members extend radially from the tube bundle shroud and connect the tube bundle shroud and the cylinder portion to each other. In this way, the first support member is supported by the cylinder portion of the steam generator through the second support member and the third support member, and the tube bundle shroud is supported to the cylinder portion by the third support member. Further, since the tube bundle shroud is reinforced by the first support member and the second support member, the strength is improved. As a result, since the heat transfer tube of the U-bent portion vibrated by an earthquake is supported through the first support member, the second support member, the tube bundle shroud, and the third support member, the quake resistance of the U-bent portion is improved.

According to a fifth aspect of the invention, in the first to the forth aspects of the invention, a plurality of the first support members may be disposed in an overlapping manner toward the top portion of the U-bent portion. In this way, the quake resistance may be improved by further reliably suppressing the vibration of the U-bent portion.

Advantageously, in the steam generator, the plurality of second support members overlap each other and the plurality of second members overlap each other between the plurality of the plurality of first support members when viewed from a direction in which the plurality of first support members are arranged. In this way, it is possible to suppress the disturbance of the flow of the secondary cooling water from the tube support plate toward the top portion of the U-bent portion.

According to another aspect of the present invention, a steam generator with a U-bent portion obtained by collectively disposing circular-arc portions of upper ends of a plurality of inverse U-shaped heat transfer tubes, includes: partition plates that are inserted between the heat transfer tubes of the U-bent portion so as to divide the U-bent portion into a plurality of portions and are supported by a support portion to a cylinder portion accommodating the heat transfer tubes of the steam generator.

According to the steam generator, since the deformation of the heat transfer tube inside the U-bent portion is suppressed by the partition plate, the quake resistance of the U-bent portion may be ensured by decreasing the stress applied to the U-bent portion with respect to the excessive excitation force to the allowable stress or less.

Advantageously, in the steam generator, the partition plates are provided at a plurality of positions.

When an oscillation is transmitted to the steam generator due to an earthquake or the like, a large excitation force is applied to the U-bent portion at the upper end side of the heat transfer tube. For this reason, according to the steam generator of the invention, since the deformation of the heat transfer tube is suppressed at a plurality of positions inside the U-bent portion by the partition plate, the quake resistance of the U-bent portion may be further ensured by decreasing the stress applied to the U-bent portion with respect to the excessive excitation force to the allowable stress or less.

Advantageously, in the steam generator, the partition plates are provided so as to overlap each other.

According to the steam generator, since the deformation of the heat transfer tube inside the U-bent portion is suppressed by the plurality of partition plates overlapping one another to improve the rigidity thereof, the quake resistance of the U-bent portion may be further ensured by decreasing the stress applied to the U-bent portion with respect to the excessive excitation force to the allowable stress or less.

Advantageously, in the steam generator, the partition plates are provided with a penetration hole.

According to the steam generator, it is possible to ensure the quake resistance of the U-bent portion by the partition plates and to ensure the flowability of the secondary cooling water by the penetration hole. Thus, it is possible to ensure the steam generation efficiency.

Advantageously, in the steam generator, the penetration hole is formed as an orifice.

According to the steam generator, it is possible to ensure the steam generation efficiency by ensuring the flowability of the secondary cooling water by an orifice. Then, when the partition plate is vibrated due to an earthquake, the vibration may be damped.

Advantageously, in the steam generator, the support portion is a tube support plate that is supported to the cylinder portion so as to fix the heat transfer tubes.

According to the steam generator, since the support portion supports the partition plate, the partition plate may be supported to the cylinder portion by being inserted between the heat transfer tubes of the U-bent portion.

Advantageously, in the steam generator, the support portion includes an annular portion that surrounds the U-bent portion at the inside of a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion, a tube bundle shroud inner member that is interposed between the tube bundle shroud and the annular portion at the inside of the tube bundle shroud and supports the annular portion, and a tube bundle shroud outer member that is interposed between the tube bundle shroud and the cylinder portion at the outside of the tube bundle shroud and supports the tube bundle shroud inner member, and the partition plate is supported by the annular portion.

According to the steam generator, since the support portion supports the partition plate, the partition plate may be supported to the cylinder portion by being inserted between the heat transfer tubes of the U-bent portion.

Advantageously, in the steam generator, the support portion includes a tube bundle shroud outer member that is interposed between the tube bundle shroud and the cylinder portion at the outside of a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion, and an end of the partition plate extending to the tube bundle shroud is supported by the tube bundle shroud outer member.

According to the steam generator, since the support portion supports the partition plate, the partition plate may be supported to the cylinder portion by being inserted between the heat transfer tubes of the U-bent portion.

Advantageously, in the steam generator, the support portion includes a tube bundle shroud inner member that is provided at the inside of a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion and a tube bundle shroud outer member that is interposed between the tube, bundle shroud and the cylinder portion at the outside of the tube bundle shroud and supports the tube bundle shroud inner member, and the partition plate is supported so as to be sandwiched between the plurality of tube bundle shroud inner members.

According to the steam generator, since the support portion supports the partition plate, the partition plate may be supported to the cylinder portion by being inserted between the heat transfer tubes of the U-bent portion.

Advantageously, in the steam generator, a bonding mechanism is provided between the support portion and the partition plate or between members of the support portion so as to bond them to each other with a predetermined gap therebetween.

According to the steam generator, since the bonding mechanism is provided between the support portion and the partition plate or between the members of the support portion so as to bond them to each other with a predetermined gap therebetween, the members are not strongly fixed to each other. For this reason, it is possible to prevent the vibration generated during the general operation of the steam generator from being transmitted to the cylinder portion or the partition plate.

Advantageously, in the steam generator, a damping mechanism is provided between the support portion and the partition plate or between members of the support portion so as to connect them to each other and damps a relative movement therebetween while allowing the movement.

According to the steam generator, since the damping mechanism is provided between the support portion and the partition plate or between the members of the support portion so as to damp the oscillation generated therebetween, the quake resistance of the U-bent portion may be further ensured.

According to still another aspect or the present invention, a steam generator includes: a U-bent portion in which a plurality of bent portions of a plurality of heat transfer tubes are formed in a U-shape so as to form a semi-spherical shape on the whole and are disposed in the out-of-plane direction perpendicular to a plane including the bent portions; a tube bundle shroud that surrounds the U-bent portions at the outer peripheral side thereof; and a beam member that is disposed near a top portion of the U-bent portion so as to have a gap with respect to the U-bent portion and has both ends fixed to an inner peripheral surface of the tube bundle shroud so that the beam member extends in the out-of-plane direction along a semi-spherical surface of the U-bent portion.

According to the characteristic steam generator, when the earthquake acceleration is applied to the U-bent portion in the out-of-plane direction so that the U-bent portion is vibrated, the vibration of the U-bent portion in the out-of-plane direction may be received by the beam member that extends along the semi-spherical surface of the U-bent portion in the out-of-plane direction. Further, since the beam member is disposed with a gap with respect to the U-bent portion, the restraining force of the U-bent portion may be reduced. For this reason, when the steam generator is operated, the vibration abrasion or the like of the heat transfer tube or the like caused by the secondary cooling water passing between the beam member and the U-bent portion is suppressed.

Advantageously, the steam generator further includes a movement regulation portion that regulates a relative movement of the U-bent portion with respect to the beam member in the out-of-plane direction.

Accordingly, since the vibration of the U-bent portion is reliably suppressed by the beam member in the event of an earthquake, the restraining force of the U-bent portion may be reduced during the operation of the steam generator.

Advantageously, in the steam generator, the movement regulation portion includes a plurality of vibration preventing members that are disposed between the adjacent heat transfer tubes in the out-of-plane direction so as to connect the adjacent heat transfer tubes to each other and has an end protruding from the semi-spherical surface, a bridge that connects ends of the plurality of vibration preventing member to each other in the extension direction of the bent portion, and a regulation member that is provided in the beam member and sandwiches the bridge with a predetermined gap therebetween in the out-of-plane direction.

The regulation member attached to the beam member does not restrain the heat transfer tube that is supported by the bridge through the vibration preventing member. For this reason, it is possible to suppress the vibration abrasion or the like of the bridge caused by the secondary cooling water passing through the gap formed between the regulation member and the U-bent portion during the operation of the steam generator. Thus, it is possible to reduce an influence on the resistance of the heat transfer tube with respect to the flow oscillation and hence to suppress degradation in the resistance. Meanwhile, when the U-bent portion, the vibration preventing member, and the bridge are vibrated together due to an earthquake or the like, the regulation member regulates the vibration of the bridge in the out-of-plane direction. Accordingly, it is possible to suppress the vibration of the heat transfer tube connected to the bridge through the vibration preventing member in the out-of-plane direction.

Advantageously, the steam generator further includes: a cylinder portion that is provided at the outer peripheral side of the tube bundle shroud and accommodates the tube bundle shroud and the plurality of heat transfer tubes; and an outer tube support member that is disposed throughout an inner peripheral surface of the cylinder portion and an outer peripheral surface of the tube bundle shroud and supports the tube bundle shroud.

Accordingly, since the vibration of the U-bent portion in the out-of-plane direction may be received by the cylinder portion through the beam member, the tube bundle shroud, and the support member, the strong quake resistance of the U-bent portion may be further obtained.

Advantageously, in the steam generator, plurality of the beam members are provided with a gap therebetween in the extension direction of the bent portion.

Accordingly, it is possible to further reliably suppress the vibration of the U-bent portion in the out-of-plane direction.

Advantageously, in the steam generator, each beam member is obtained by connecting a plurality of divided beams in the out-of-plane direction.

Generally, since various structures are provided near the top portion of the U-bent portion in the steam generator, it is difficult to carry and install the single beam member to the installation position. On the contrary, since the beam member includes the plurality of divided beams, the respective divided beams may be easily carried to the installation position of the beam member. Accordingly, the beam members may be easily installed by connecting the divided beams at the installation position of the beam member.

Advantageously, in the steam generator, the beam member forms a truss structure.

Accordingly, since it is possible to reduce the cross-sectional area perpendicular to the extension direction of the beam member while ensuring the rigidity of the beam member, it is possible to reduce the fluid resistance of the secondary cooling water. Thus, it is possible to obtain a function of suppressing the vibration of the U-bent portion in the out-of-plane direction by the beam member without degrading the performance of the steam generator.

Advantageous Effects of Invention

The invention may ensure the quake resistance and the resistance with respect to the flow oscillation of the U-bent portion. Further, in the invention, since the vibration of the U-bent portion in the out-of-plane direction may be received by the beam member extending along the semi-spherical surface of the U-bent portion in the out-of-plane direction, the quake resistance of the U-bent portion in the out-of-plane direction may be ensured. Further, since the beam member is disposed with a gap with respect to the U-bent portion, it is possible to suppress the vibration abrasion or the like of the heat transfer tube or the like caused by the secondary cooling water passing between the beam member and the U-bent portion and hence to ensure the resistance with respect to the flow oscillation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating a steam generator according to an embodiment.

FIG. 2 is a diagram illustrating a bent portion of a heat transfer tube.

FIG. 3 is a plan view illustrating a. U-bent portion.

FIG. 4 is a cross-sectional view taken along the line A-A of FIG. 3.

FIG. 5 is a perspective view illustrating the U-bent portion.

FIG. 6 is a perspective view illustrating a quake-resistant structure of a steam generator according to a first embodiment.

FIG. 7 is a plan view illustrating the quake-resistant structure of the steam generator according to the first embodiment.

FIG. 8 is an enlarged view illustrating a part of the quake-resistant structure of the steam generator according to the first embodiment.

FIG. 9 is a diagram illustrating a relation between a regulation member and a bridge of the quake-resistant structure of the steam generator according to the first embodiment.

FIG. 10 is a plan view illustrating a quake-resistant structure according to a modified example of the first embodiment.

FIG. 11 is a diagram illustrating a modified example of the regulation member of the first embodiment.

FIG. 12 is a diagram illustrating a modified example of the regulation member of the first embodiment.

FIG. 13 is a diagram illustrating a modified example of the regulation member of the first embodiment.

FIG. 14 is a diagram illustrating a modified example of the regulation member of the first embodiment.

FIG. 15 is a side view illustrating a partition plate of a steam generator according to a second embodiment.

FIG. 16 is a cross-sectional view taken along the line B-B of FIG. 15.

FIG. 17 is a side view illustrating another embodiment of the partition plate of the steam generator according to the second embodiment.

FIG. 18 is a side view illustrating another embodiment of the partition plate of the steam generator of the second embodiment.

FIG. 19 is a cross-sectional view illustrating the partition plate of the steam generator according to the second embodiment.

FIG. 20 is a cross-sectional view illustrating the partition plate of the steam generator according to the second embodiment.

FIG. 21 is a side view illustrating a support portion of the steam generator according to the second embodiment.

FIG. 22 is a perspective view illustrating the support portion of the steam generator according to the second embodiment.

FIG. 23 is a plan view illustrating the support portion of the steam generator according to the second embodiment.

FIG. 24 is a side view illustrating another embodiment of the support portion of the steam generator according to the second embodiment.

FIG. 25 is a side view illustrating another embodiment of the support portion of the steam generator according to the second embodiment.

FIG. 26 is a schematic diagram illustrating a bonding mechanism of the steam generator according to the second embodiment.

FIG. 27 is a schematic diagram illustrating a damping mechanism of the steam generator according to the second embodiment.

FIG. 28 is a schematic diagram illustrating another embodiment of the damping mechanism of the steam generator according to the second embodiment.

FIG. 29 is a perspective view illustrating a U-bent portion of a steam generator according to a third embodiment.

FIG. 30 is a longitudinal sectional view illustrating a relation of a vibration preventing member, a holding member, and a bridge of the steam generator according to the third embodiment in the out-of-plane direction.

FIG. 31 is a plan view illustrating a quake-resistant structure of the steam generator according to the third embodiment.

FIG. 32 is a longitudinal sectional view of the quake-resistant structure of the steam generator according to the third embodiment.

FIG. 33 is a longitudinal sectional view illustrating a relation of a bridge and a regulation member of the quake-resistant structure of the steam generator according to the third embodiment in the out-of-plane direction.

FIG. 34 is a longitudinal sectional view illustrating another embodiment of the quake-resistant structure of the steam generator according to the third embodiment.

FIG. 35 is a cross-sectional view illustrating a connection position of divided beams of the embodiment illustrated in FIG. 34.

FIG. 36 is a cross-sectional view illustrating a connection position of the divided beams of the embodiment illustrated in FIG. 34.

FIG. 37 is a longitudinal sectional view illustrating another embodiment of the quake-resistant structure of the steam generator according to the third embodiment.

DESCRIPTION OF EMBODIMENTS

Modes (embodiments) for carrying out the invention will be described in detail by referring to the drawings. The present invention is not limited to the description of the embodiments below. Further, the components described below include a component which may be easily supposed by the person skilled in the art and a component which has substantially the same configuration. Furthermore, the configurations described below may be appropriately combined with one another. Further, various omissions, replacements, or modifications of the components may be made without departing from the spirit of the invention. In this embodiment, the down direction indicates the vertical direction (gravity acting direction), and the up direction indicates the opposite side in the vertical direction.

FIG. 1 is a schematic diagram illustrating a steam generator according to the embodiment. FIG. 2 is a diagram illustrating a bent portion of a heat transfer tube. A steam generator 1 is used in, for example, a pressurized water reactor (PWR). The pressurized water reactor uses light water as reactor coolant and neutron moderator. The pressurized water reactor uses light water as primary coolant. The pressurized water reactor sends primary coolant (primary cooling water) as hot and pressurized water which is not boiled throughout a reactor core to the steam generator 1. In the steam generator 1, the heat of the hot and pressurized primary cooling water is transmitted to secondary coolant (secondary cooling water) so as to change secondary cooling water into steam. The steam is sent to a steam turbine so as to drive the steam turbine. Since an input shaft of a power generator is connected to an output shaft of the steam turbine, the power generator which is driven by the steam turbine generates power.

The steam generator 1 includes a cylinder portion 2. The cylinder portion 2 has a hermetic hollow cylindrical shape extending in the up and down direction, and is formed as a structure of which the diameter of a lower half portion is smaller than that of an upper half portion. In the cylinder portion 2, a channel head 7 is disposed near one end of the cylinder portion and a steam discharge port 12 is disposed near the other end thereof. The steam generator 1 is provided so that the channel head 7 faces the downside and the steam discharge port 12 faces the upside.

A cylindrical tube bundle shroud (wrapper tube) 3 which is disposed with a predetermined gap with respect to the inner wall surface of the cylinder portion 2 is provided from the inside of the lower half portion of the cylinder portion 2 to the upper half portion thereof. The lower end of the tube bundle shroud 3 extends to a tube sheet 4 which is disposed at the lower position inside the lower half portion of the cylinder portion 2. The inside of the tube bundle shroud 3 is provided with a heat transfer tube group 51 having a plurality of heat transfer tubes 5 with U-shaped bent portions 5U illustrated in FIG. 2. Then, the tube bundle shroud 3 and the plurality of heat transfer tubes 5 are accommodated by the cylinder portion 2 provided at the outer peripheral side of the tube bundle shroud 3. The respective heat transfer tubes 5 are arranged so that the U-shaped portions of the bent portions face to upside, that is, the steam discharge port 12, the ends facing the downside, that is, the channel head 7 are supported by the tube sheet 4, and the intermediate portions thereof are supported by a plurality of tube support plates 6. The assembled portion of the U-shaped bent portions of the plurality of heat transfer tubes 5 is a U-bent portion 18. The U-bent portion 18 is disposed near the upside of the heat transfer tube group 51, that is, the steam discharge port 12. The tube support plate 6 is provided with a plurality of penetration holes, and the respective heat transfer tubes 5 pass through the penetration holes in a non-contact state.

The lower end of the cylinder portion 2 is provided with the channel head 7. The inside of the channel head 7 is divided by a partition wall 8 into an inlet chamber 71 and an outlet chamber 72. One ends of the respective heat transfer tubes 5 communicate with the inlet chamber 71 and the other ends of the respective heat transfer tubes 5 communicate with the outlet chamber 72. Further, the inlet chamber 71 is provided with an inlet nozzle 711 which communicates with the outside of the cylinder portion 2, and the outlet chamber 72 is provided with an outlet nozzle 721 which communicates with the outside of the cylinder portion 2. Then, the inlet nozzle 711 is connected with a cooling water tube through which the primary cooling water is sent from the pressurized water reactor. The outlet nozzle 721 is connected with a cooling water tube through which the primary cooling water subjected to the heat exchange process is sent to the pressurized water reactor.

The upper half portion of the cylinder portion 2 is provided with a steam-water separator 9 which separates fed water W into steam S and hot water and a moisture separator 10 which removes moisture of the separated steam S so that the steam substantially becomes dry steam. A water feeding tube 11 which feeds the secondary cooling water from the outside into the cylinder portion 2 is inserted between the steam-water separator 9 and the heat transfer tube group 51. Further, the upper end of the cylinder portion 2 is provided with the steam discharge port 12. Further, the inside of the lower half portion of the cylinder portion 2 is provided with a water feeding line 13 which causes the secondary cooling water fed from the water feeding tube 11 into the cylinder portion 2 to flow down between the cylinder portion 2 and the tube bundle shroud 3, to be turned back by the tube sheet 4, and to rise along the heat transfer tube group 51. Furthermore, the steam discharge port 12 is connected with a cooling water tube which sends the steam to the turbine, and the water feeding tube 11 is connected with a cooling water tube which is used to supply the secondary cooling water obtained by cooling the steam used in the turbine by the condenser.

In the steam generator 1, the primary cooling water which is heated by the pressurized water reactor is sent to the inlet chamber 71, circulates so as to pass through the plurality of heat transfer tubes 5, and reaches the outlet chamber 72. Meanwhile, the secondary cooling water which is cooled by the condenser is sent to the water feeding tube 11, passes through the water feeding line 13 inside the cylinder portion 2, and rises along the heat transfer tube group 51. At this time the hot and pressurized primary cooling water and the secondary cooling water exchange heat therebetween inside the cylinder portion 2. Then, the cooled primary cooling water is returned from the outlet chamber 72 to the pressurized water reactor. Meanwhile, the secondary cooling water which exchanges heat with the hot and pressurized primary cooling water rises inside the cylinder portion 2 and is separated by the steam-water separator 9 into steam and hot water. Then, moisture is removed from the separated steam by the moisture separator 10, and the steam is sent to the turbine.

FIG. 3 is a plan view illustrating the U-bent portion, FIG. 4 is a cross-sectional view taken along the line A-A of FIG. 3, and FIG. 5 is a perspective view illustrating the U-bent portion. In the steam generator 1, a fluid excitation oscillation occurs in inverse U-shaped bent portions 5U when the primary cooling water passes through the respective heat transfer tubes 5. Therefore, the bent portions 5U of the heat transfer tubes 5 are provided with a vibration preventing member. The upper end of the heat transfer tube group 51 is the U-bent portion 18. The bent portion 18 is a portion obtained by collectively arranging the inverse U-shaped bent portions 5U of the plurality of heat transfer tubes 5. As illustrated in FIG. 4, heat transfer tube layers 5A are formed by arranging the heat transfer tubes 5 from the center of the heat transfer tube layers toward the outside (upside) so that the curvature radius of the bent portion 5U becomes larger. Further, as illustrated in FIG. 3, the upper end of the heat transfer tube group 51 is formed in a semi-spherical shape by changing the curvature radiuses of the bent portions 5U of the outermost peripheral heat transfer tubes while laterally overlapping the arranged heat transfer tube layers 5A. That is, the U-bent portion 18 has a semi-spherical shape, and the portion closest to the steam discharge port 12 illustrated in FIG. 1 becomes the top portion of the U-bent portion 18.

As illustrated in FIG. 5, the vibration preventing member 14 is inserted between the heat transfer tube layers 5A in the out-of-plane direction D1. As illustrated in FIG. 4, the vibration preventing member 14 is substantially bent overlapping in a V-shape at a position deviated from the center line S of the circular-arc portion 5U of the heat transfer tube layer 5A (in FIG. 4, the V-shaped vibration preventing member is denoted by the sign 14A). Further, the vibration preventing member 14 is formed in a linear shape along the center line S at the position of the center (the center line S illustrated in FIG. 4) of the circular-arc portion 5U of the heat transfer tube layer 5A (in FIG. 4, the linear vibration preventing member is denoted by the sign 14B).

The bent portion of the V-shaped vibration preventing member 14A is disposed at the uniform diameter portions of the respective heat transfer tube layers 5A overlapping in the out-of-plane direction. D1. Then, both ends of the vibration preventing member 14A protrude toward the outside of the circular-arc portion 5U of the heat transfer tube 5 with the largest diameter. Further, in the vibration preventing member 14A, a small V-shaped vibration preventing member is disposed inside a large. V-shaped vibration preventing member so as to make a pair, and for example, two pairs are disposed at the semi-circular portion of the heat transfer tube 5.

The linear vibration preventing member 14B is disposed along the center line S of the circular-arc portion 5U of the heat transfer tube layer 5A. Then, the vibration preventing member 14B is attached to the uppermost tube support plate 6 in the steam generator 1 while one end of the vibration preventing member protrudes toward the outside of the circular-arc portion 5U of the heat transfer tube 5 having the largest diameter. Furthermore, the vibration preventing member 14B may not be provided in accordance with the type of the steam generator 1. In the vibration preventing member 14 (14A, 14B), the portion which is inserted between the respective heat transfer tube layers 5A overlapping in the out-of-plane direction D1 is formed of a material (for example, SUS405) which desirably suppress the vibration.

The vibration preventing members 14 (14A, 14E) are arranged so that the ends protruding toward the outside of the circular-arc portions 5U of the heat transfer tubes 5 are arranged in series along the circular-arc of the semi-spherical shape in the stacking direction (the out-of-plane direction D1) of the heat transfer tube layers 5A. Further, the ends protruding toward the outside of the circular-arc portions 5U of the heat transfer tubes 5 are provided with bonding members 15. As illustrated in FIGS. 3 to 5, the bonding members 15 which are provided in the vibration preventing member 14 are welded at holding members 16 thereof. Each holding member 16 is a circular-arc bar-like member which is attached along the semi-spherical outer periphery of the heat transfer tube group 51. The plurality of holding members 16 are arranged in a direction (the in-plane direction D2) perpendicular to a direction (the out-of-plane direction D1) in which the plurality of heat transfer tubes 5 overlap one another. The plurality of holding members 16 are welded to the respective bonding members 15 so as to connect the ends of the vibration preventing members 14 (14A, 14B) arranged in series along the circular-arc of the semi-spherical shape in the stacking direction (the out-of-plane direction D1) of the heat transfer tube layers 5A. Each holding member 16 is attached to the heat transfer tube group 51 by welding both ends of a U-shaped attachment portion 16 a inserted between the outermost peripheral heat transfer tube 5 and the heat transfer tube 5 inside the outermost peripheral heat transfer tube. Accordingly, the vibration preventing member 14 is attached to the heat transfer tube group 51 through the holding member 16. Further, as illustrated in FIG. 5, a bridge 17 is welded to a part of the bonding members 15 of the plurality of vibration preventing members 14 provided with a gap therebetween in the out-of-Jane direction D1. More specifically, the bonding member 15 of the vibration preventing member 14 protrudes toward the outside of the semi-spherical surface in the radial direction in relation to the other vibration preventing member 14, and the bridge 17 is welded to the protruding portion. The bridge 17 is a circular-arc and plate-like member that is disposed along the outer periphery of the U-bent portion 18, that is, the outer periphery of the semi-spherical shape of the heat transfer tube group 51 so as to extend in the in-plane direction D2. The bridge 17 extends along the extension direction of the bent portion 5U in the U-bent portion 18. In FIG. 5, one bridge 17 is illustrated, but a plurality of bridges 17 are arranged with a gap therebetween in the out-of-plane direction D1.

First Embodiment

FIG. 6 is a perspective view illustrating a quake-resistant structure of a steam generator according to a first embodiment. FIG. 7 is a plan view illustrating the quake-resistant structure of the steam generator according to the first embodiment. FIG. 8 is an enlarged view illustrating a part of the quake-resistant structure of the steam generator according to the first embodiment. FIG. 9 is a diagram illustrating a relation of a regulation member and a bridge of the quake-resistant structure of the steam generator according to the first embodiment. A quake-resistant structure (hereinafter, referred to as a quake-resistant structure) 20 of the steam generator includes an annular member 21 (21A, 21B) as a first support member, a second support member 22 (22A, 22B), and a third support member 23 (23A, 23B). The quake-resistant structure 20 includes two annular members 21, two second support members 22, and two third support members 23. In the description below, when the support members need to be distinguished from each other, the sign A is added to the support member near the tube support plate 6, and the sign A is added to the support member near the top portion 18T of the U-bent portion 18. When the support members do not need to be distinguished from each other, the signs A and B are not added to the support members.

The annular member 21 surrounds the U-bent portion 18 obtained by collectively disposing the bent portions 5U of the plurality of heat transfer tubes 5. Then, the annular member 21 is provided between the outer peripheral portion of the U-bent portion 18 and the tube bundle shroud 3 surrounding the outer peripheral portion so as to have a predetermined gap with respect to the U-bent portion 18. The second support member 22 is provided between the annular member 21 and the tube bundle shroud 3, and supports the annular member 21 by the tube bundle shroud 3. The third support member 23 is attached to the cylinder portion 2 (more specifically, the inner peripheral surface of the cylinder portion 2) accommodating the plurality of heat transfer tubes 5, and supports the second support member 22. Since the tube bundle shroud 3 is interposed between the second support member 22 and the third support member 23, the third support member 23 supports the annular member 21 by the cylinder portion 2 through the tube bundle shroud 3. The annular member 21 is a structure which has a circular shape in a plan view. The annular member 21 may be obtained by forming a hollow cylindrical tube in an annular shape or forming a solid bar-like member having a circular cross-section in an annular shape.

As illustrated in FIG. 8, the plurality of second support members 22 are provided at the outside of the annular member 21 in the radial direction, and extend radially from the annular member 21 toward the tube bundle shroud 3. The plurality of third support members 23 extend in a direction parallel to the radial direction of the cylinder portion 2 from the inner surface of the cylinder portion 2 having a circular cross-section toward the tube bundle shroud 3. That is, the plurality of third support members 23 extend radially from the tube bundle shroud 3.

The end of each second support member 22 opposite to the annular member 21 is fixed to the tube bundle shroud 3 through a pedestal 27. The second support member 22 and the pedestal 27 are attached to each other by, for example, welding. The pedestal 27 is fixed to the tube bundle shroud 3 by, for example, a fastening member such as a bolt. With such a structure, the second support member 22 is fixed to the tube bundle shroud 3.

The pedestal 27 is attached to each of both ends of the third support member 23. The third support member 23 and the pedestal 27 are attached to each other by, for example, welding. The pedestal 27 near one end of the third support member 23 is fixed to the cylinder portion 2 by, for example, a fastening member such as a bolt. Further, the pedestal 27 near the other end of the third support member 23 is fixed to the tube bundle shroud by the bolt that fixes the pedestal 27 attached to the second support member 22 to the tube bundle shroud 3. With such a structure, the third support member 23 connects the cylinder portion 2 and the tube bundle shroud 3 to each other. Then, the annular member 21 is supported by the cylinder portion 2 through the second support member 22 and the third support member 23 in this embodiment, the annular member 21A near the tube support plate 6 and the annular member 21B near the top portion 18T of the U-bent portion 18 have different diameters, but are respectively supported by the cylinder portion 2 through the second support members 22A and 22B and the third support members 23A and 23B.

When the U-bent portion 18 is vibrated in a direction parallel to the radial direction of the cylinder portion 2 having a circular cross-section by an earthquake or the like, the vibration of the U-bent portion 18 may be received by the cylinder portion 2 through the annular member 21, the second support member 22, and the third support member 23, and hence the quake resistance of the U-bent portion 18 is ensured. Further, since the annular member 21 is disposed with a predetermined gap with respect to the U-bent portion 18, the restraining force of the U-bent portion 18 may be reduced. Furthermore, in this embodiment, since the annular member 21 does not restrain the heat transfer tubes 5 of the U-bent portion 18, the restraining force is 0. For this reason, when the steam generator 1 is operated, it is possible to suppress the vibration abrasion or the like of the heat transfer tubes 5 or the like due to the secondary cooling water that passes between the annular member 21 and the U-bent portion 18. As a result, the quake-resistant structure 20 which has the annular member 21 may ensure the resistance by reducing the influence on the resistance with respect to the flow resistance of the heat transfer tube 5. Further, since the annular member 21, the second support member 22, and the third support member 23 of the quake-resistant structure 20 may be attached to even the existing steam generator 1 by a repairing work, the quake resistance of the existing steam generator 1 may be improved.

In this embodiment, the annular member 21 of the quake-resistant structure 20 includes regulation members 24 illustrated in FIGS. 7 and 8. As illustrated in FIGS. 8 and 9, each regulation member 24 regulates the movement of the bridge 17 by sandwiching the bridge 17, connecting the plurality of holding members 15 connecting the ends of the plurality of vibration preventing members 14 disposed between the heat transfer tubes 5 in the U-bent portion 18, with a predetermined gap C. More specifically, the holding member 16 regulates the movement of the bridge 17 in a direction of overlapping the heat transfer tubes 5.

A regulation member 24A includes a groove portion 24S. The bridge 17 is sandwiched in the groove portion 24S with a predetermined gap C. The regulation member 24A is attached to the annular member CIA and the regulation member 24B is attached to the annular member 21B by a bonding method, for example, welding or the like. Since the regulation member 24 and the bridge 17 have a predetermined gap C (about 5 mm to 10 mm) therebetween, a gap is formed therebetween.

With such a structure, since the regulation member 24 which is attached to the annular member 21 does not restrain the heat transfer tubes 5 which are supported by the bridge 17 through the vibration preventing members 14 and the holding members 1 in the U-bent portion 18, the restraining force for the heat transfer tubes 5 is 0. For this reason, when the steam generator 1 is operated, it is possible to suppress the vibration abrasion or the like of the bridges 17 due to the secondary cooling water that passes through the gap formed between the regulation members 24 and the U-bent portion 18. As a result, the quake-resistant structure 20 with the annular member 21 may suppress degradation in resistance by suppressing the influence on the resistance with respect to the flow resistance of the heat transfer tube 5. Further, when the U-bent portion 18 and the bridges 17 are vibrated by an earthquake or the like, the regulation members 24 which are supported by the cylinder portion 2 through the annular members 21, the second support members 22, and the third support members 23 regulate the vibration of the bridges 17. Since the bridges 17 support the plurality of heat transfer tubes 5 of the U-bent portion 18, such a vibration is also regulated by the regulation members 24. Since the gap between the regulation member 24 and the bridge 17 is smaller than the gap between the annular member 21 and each of the plurality of heat transfer tubes 5 of the U-bent portion 18, it is possible to further effectively suppress the vibration of the U-bent portion 18 by using the regulation members 24. As a result, the quake-resistant structure 20 with the regulation member 24 may further reliably ensure the quake resistance of the U-bent portion 18.

In this embodiment, the plurality of annular members 21 are arranged toward the top portion 18T of the U-bent portion 18. More specifically, two annular members 21A and 21B are arranged from the tube support plate 6 toward the top portion 18T of the U-bent portion 18. In this way, it is possible to further ensure the quake resistance by further reliably suppressing the vibration of the U-bent portion 18. The number of the annular members 21 is not limited to two, and may be three or more. Further, if the quake resistance of the U-bent portion 18 may be ensured by one annular member 21, one annular member 21 may be provided.

When the quake-resistant structure 20 includes the plurality of annular members 21, it is desirable to overlap the plurality of second support members 22 and the plurality of second members 23 between the plurality of annular members 21 when viewed from a direction in which the plurality of annular members 21 are arranged. In this way, it is possible to suppress the disturbance of the flow of the secondary cooling water from the tube support plate 6 toward the top portion 18T of the U-bent portion 18. Furthermore, this does not exclude a case in which the plurality of second support members 22 overlap each other and the plurality of third support members 23 overlap each other when viewed from a direction in which the plurality of annular members 21 are arranged.

FIG. 10 is a plan view illustrating a quake-resistant structure according to a modified example of the first embodiment. In the quake-resistant structure 20 illustrated in FIG. 7, the second support members 22 and the third support members 23 extend radially from the annular members 21, but a quake-resistant structure 20 a of the modified example is different in that second support members 22 a and third support members 23 a do not extend radially from the annular member 21 a. When the second support members 22 and the third support members 23 radially extend from the annular members 21, the support members extend in a direction parallel to the radial direction of the annular member 21. That is, the second support members 22 and the third support members 23 extend in a direction perpendicular to the tangential line of the outer peripheral portion of the annular member 21. In the modified example, the second support members 22 a and the third support members 23 a extend in a direction other than the direction perpendicular to the tangential line of the outer peripheral portion of the annular member 21 a. Even in this way, the annular members 21 a are supported by the cylinder portion 2 through the second support member 22 a and the third support member 23 a.

In this embodiment, the annular members 21 and 21 a are described as an example of the first support member, but the first support member is not limited to the annular member 21 and the like. That is, the first support member may be a member that surrounds the periphery of the U-bent portion 18 and is provided between the outer periphery and the tube bundle shroud 3 surrounding the outer peripheral portion of the U-bent portion 18 so as to have a predetermined gap with respect to the U-bent portion 18. Thus, the first support member may be, for example, a basket-like member that surrounds the U-bent portion 18.

(Modified Example of Regulation Member of the First Embodiment)

FIGS. 11 to 14 are diagrams illustrating modified examples of the regulation member of the first embodiment. The regulation member according to the modified example is different in that an orifice is provided at a portion facing the bridge. A regulation member 24 a illustrated in FIGS. 11 and 12 includes a plurality of orifices 25 which penetrate an outer portion 24Y from the portion facing the bridge 17 a inside the groove portion 24S. Both side surfaces 17Sa of the bridge 17 a are sandwiched in the regulation member 24 a, but the regulation member 24 a includes the orifices 25 at the portions facing both side surfaces 17Sa. Furthermore, in the bridge 17 a, the portion (the bridge end) 17Ta which is sandwiched in the groove portion 24S of the regulation member 24 a has a width larger than those of the other portions. The regulation member 24 a includes extension portions 24E which extend from both outer portions 24Y to the opening portion of the groove portion 24S. Since the dimension between both extension portions 24E is smaller than that of the bridge end 17Ta, the separation of the bridge 17 a from the groove portion 24S is prevented. As illustrated in FIG. 12, the inner diameter of the inner portion of the orifice 25 is smaller than that of the opening portion of the orifice, but the orifice 25 is not limited to the shape.

A predetermined gap Ca is formed between the groove portion 24S of the regulation member 24 a and both side surfaces 17Sa of the bridge end 17Ta. Further, a predetermined gap Cb is formed between the extension portion 24E and the bridge end 17Ta. Since the regulation member 24 has the orifices 25, the inflow and the outflow of the secondary cooling water inside the groove portion 24S occur from the orifices 25 when the bridge end. Ta moves inside the groove portion 24S. Accordingly, since it is possible to obtain a damping action that damps the vibration of the bridge 17 a, it is possible to alleviate an abrupt change in acceleration acting on the plurality of heat transfer tubes 5 of the U-bent portion 18. As a result, the quake resistance of the U-bent portion 18 is further improved. Furthermore, the inflow and the outflow of the secondary cooling water occur even from the predetermined gap Cb formed between the extension portion 24E and the bridge end 17Ta. As a result, since it is possible to obtain a damping action that damps the vibration of the bridge 17 a even by this configuration, the quake resistance of the U-bent portion 18 is further improved.

A regulation member 24 b illustrated in FIG. 13 includes an intermediate support member 26 which has a. U-shaped cross-section, faces both side surfaces 17S of the bridge 17, and is provided inside the groove portion 24S. A spring 28 is disposed between the intermediate support member 26 and the regulation member 24 b. The spring 28 applies a force directed toward the bridge 17 to the intermediate support member 26. Further, as in the regulation member 24 a illustrated in FIGS. 11 and 17, the regulation member 24 b includes the plurality of orifices 25 which penetrate the outer portion 24Y from the portion facing the bridge 17 inside the groove portion 24S. With such a structure, the regulation member 24 b may obtain an impact absorbing action using the spring 28 in addition to the action that damps the vibration of the bridge 17 by the orifices 25. As a result, the regulation member 24 b may further improve the quake resistance of the U-bent portion 18.

As in the regulation member 24 b illustrated in FIG. 13, a regulation member 24 c illustrated in FIG. 14 includes an intermediate support member 26 c that faces both side surfaces 17 r of the bridge 17 and is provided inside the groove portion 24S, but has a difference in that two plate-like intermediate support members 26 c nip the bridge end 17Tc. For this reason, two intermediate, support members 26 c are close to the bridge end 17Tc. Further, the bridge, end 17Tc has a circular cross-section. In this way, the inclination of the bridge 17 c with respect to the intermediate support member 26 c may be allowed.

The spring 28 is disposed between each intermediate support member 26 c and the regulation member 24 c. The spring 28 applies a force directed toward the bridge 17 to the intermediate support member 26. With such a structure, as in the regulation member 24 b, the regulation member 24 c may obtain an impact absorbing action using the spring 28 in addition to the action that damps the vibration of the bridge 17 c by the orifices 25. As a result, the regulation member 24 c may further improve the quake resistance of the U-bent portion 18.

Second Embodiment

In the steam generator 1 of the embodiment, a partition plate is provided in the U-bent portion 18 so as to ensure the quake resistance of the U-bent portion 18. FIG. 15 is a side view illustrating a partition plate of the steam generator according to a second embodiment. FIG. 16 is a gross-sectional view taken along the line B-B of FIG. 15.

As illustrated in FIG. 15, a partition plate 30 is inserted between the heat transfer tubes 5 of the U-bent portion 18. Specifically, the partition plate 30 is inserted between the heat transfer tube layers 5A. Further, the vibration preventing member 14 is provided between the heat transfer tube layer 5A and the partition plate 30. That is, the partition plate 30 is disposed at a position where at least one heat transfer tube layer 5A is disposed so as to replace the heat transfer tube layer 5A. Then, as illustrated in FIG. 16, the partition plate 30 is provided so as to overlap the entire adjacent heat transfer tube layer 5A. The partition plate 30 is fixed to the tube support plate 6 as the support portion which is supported by the cylinder portion 2 through the tube bundle shroud 3. Accordingly, the partition plate is supported to the cylinder portion 2 accommodating the heat transfer tubes 5 of the steam generator 1 and is provided so as to divide the U-bent portion 18 into a plurality of portions. The partition plate 30 illustrated in FIGS. 15 and 16 is provided at the center (the position of the center line. S) of the U-bent portion 18 so as to divide the U-bent portion 18 into two portions. Furthermore, the partition plate 30 may be disposed so as to contact the heat transfer tube 5, the vibration preventing member 14, the holding member 16, and the attachment portion 17 as the constituents of the U-bent portion 18 or to be separated therefrom.

According to the steam generator 1, since the deformation of the heat transfer tube 5 inside the U-bent portion 18 is suppressed by the partition plate 30, it is possible to ensure the quake resistance of the U-bent portion 18 by decreasing the stress applied to the U-bent portion 18 with respect to the excessive excitation force to the allowable stress or less.

FIG. 17 is a side view illustrating another embodiment of the partition plate of the steam generator according to the second embodiment. In the embodiment illustrated in FIG. 17, the partition plates 30 are provided at a plurality of positions. Each partition plate 30 is inserted between the heat transfer tubes 5 at a plurality of (here, two) positions of the U-bent portion 18. Specifically, the partition plate 30: is inserted between the heat transfer tube layers 5A. Further, the vibration preventing member 14 is provided between the heat transfer tube layer 5A and the partition plate 30. That is, the partition plate 30 is disposed at a position where at least one heat transfer tube layer 5A is disposed so as to replace the heat transfer tube layer 5A. Then, the partition plate 30 is provided so as to overlap the entire adjacent heat transfer tube layer 5A. The partition plate 30 is fixed to the tube support plate 6 as the support portion which is supported by the cylinder portion 2 through the tube bundle shroud 3. Accordingly, the partition plate is supported to the cylinder portion 2 accommodating the heat transfer tubes 5 of the steam generator 1, and is provided so as to divide the U-bent portion 1B into a plurality of portions. The partition plate 30 illustrated in FIG. 17 is provided so as to divide the U-bent portion 18 into three portions in the horizontal direction. Furthermore, the partition plate 30 may be disposed so as to contact the heat transfer tube 5, the vibration preventing member 14, the holding member 16, and the attachment portion 17 as the constituents of the U-bent portion 18 or to be separated therefrom.

When an oscillation is transmitted to the steam generator 1 by an earthquake or the like, a large excitation force is applied to the U-bent portion 18 at the upper end side of the heat transfer tube group 51 of which the end facing the downside with respect to the tube sheet 4. In particular, the excitation force is easily applied in a direction of overlapping the heat transfer tube layers 5A constituting the heat transfer tube group 51. For this reason, according to the steam generator 1 of the second embodiment, since the deformation of the heat transfer tubes 5 at a plurality of positions inside the U-bent portion 18 is suppressed by the partition plate 30, it is possible to further ensure the quake resistance of the U-bent portion 18 by decreasing the stress applied to the U-bent portion 18 with respect to the excessive excitation force to the allowable stress or less.

FIG. 18 is a side view illustrating another embodiment of the partition plate of the steam generator according to the second embodiment. In the embodiment illustrated in FIG. 18, the partition plate 30 is inserted between the heat transfer tubes 5 of the U-bent portion 18. Specifically, the partition plate 30 is provided by overlapping a plurality of (here, five) partition plates 30 a, and is inserted between the heat transfer tube layers 5A. Further, the vibration preventing member 14 is provided between the heat transfer tube layer 5A and the partition plate 30. That is, the partition plate 30: is disposed at a position where at least three heat transfer tube layers 5A are disposed so as to replace the heat transfer tube layer 5A and the vibration preventing member 14. Then, the partition plate 30: is provided so as to overlap the entire adjacent heat transfer tube layer 5A. The partition plate 30 is fixed to the tube support plate 6 as the support portion which is supported by the cylinder portion 2 through the tube bundle shroud 3. Accordingly, the partition plate is supported to the cylinder portion 2 accommodating the heat transfer tube 5 of the steam generator 1, and is provided so as to divide the U-bent portion 18 into a plurality of portions. The partition plate 30 illustrated in FIG. 18 is provided at the center (the position of the center line S) of the U-bent portion 18 so as to divide the U-bent portion 18 into two portions. Furthermore, the partition plate 30 may be disposed so as to contact the heat transfer tube 5, the vibration preventing member 14, the holding member 16, and the attachment portion 17 as the constituents of the U-bent portion 18 or to be separated therefrom.

According to the steam generator 1, since the deformation of the heat transfer tubes 5 inside the U-bent portion 18 is suppressed by the partition plates 30 which overlap each other so as to improve the rigidity thereof, it is possible to further ensure the quake resistance of the U-bent portion 18 by decreasing the stress applied to the U-bent portion 18 with respect to the excessive excitation force to the allowable stress or less.

Furthermore, in this embodiment, the partition plate 30 is provided between the heat transfer tubes 5 (the heat transfer tube layers 5A), and the vibration preventing member 14 is provided between the partition plate 30 and the heat transfer tube 5. For this reason, when a fluid excitation oscillation occurs, it is possible to appropriately suppress the deflection of the heat transfer tube 5 (the heat transfer tube layer 5A) adjacent to the partition plate 30 by the vibration preventing member 14.

FIG. 19 is a cross-sectional view illustrating the partition plate of the steam generator according to the second embodiment. In the embodiment illustrated in FIG. 19, penetration holes 31 are provided in the partition plate 30. The plurality of penetration holes 31 are provided so as to penetrate the plate thickness of the partition plate 30.

According to the steam generator 1, it is possible to ensure the quake resistance of the U-bent portion 18 by the partition plate 30 and to ensure the flowability of the secondary cooling water by the penetration hole 31. Accordingly, it is possible to ensure the steam generation efficiency. Furthermore, as the partition plate 30 with the penetration holes 31, the partition plate 30 may be formed in a mesh shape or a lattice shape other than the configuration in which the holes penetrate the plate member.

FIG. 20 is a cross-sectional view illustrating the partition plate of the steam generator according to the second embodiment. In the embodiment illustrated in FIG. 20, the penetration hole 31 is formed as an orifice.

According to the steam generator 1, the steam generation efficiency may be ensured by ensuring the flowability of the secondary cooling water through the hole. Then, when the partition plate 30 is vibrated due to an earthquake or the like, the vibration may be damped.

FIG. 21 is a side view illustrating the support portion of the steam generator according to the second embodiment FIG. 22 is a perspective view illustrating the support portion of the steam generator according to the second embodiment, and FIG. 23 is a plan view illustrating the support portion of the steam generator according to the second embodiment.

As illustrated in FIG. 21, a support portion 35 includes annular portions 35 a, tube bundle shroud inner members 35 b, and tube bundle shroud outer members 35 c.

As illustrated in FIGS. 21 to 23, the annular portions 35 a are provided at the inside of the tube bundle shroud 3 surrounding the outer peripheral portion of the U-bent portion 18 so as to surround the U-bent portion 18. In this embodiment, two annular portions 35 a are disposed at the upper and lower sides. Each annular portion 35 a may be obtained by forming a hollow cylindrical tube in an annular shape or forming a solid bar-like body in an annular shape.

As illustrated in FIGS. 21 to 23, the tube bundle shroud inner members 35 b are interposed between the tube bundle shroud 3 and the annular portions 35 a at the inside of the tube bundle shroud 3 so as to support the respective annular portions 35 a. The tube bundle shroud inner members 35 b are provided at the outside of the respective annular portions 35 a in the radial direction, and are formed as a plurality of bar-like bodies extending radially from the annular portion 35 a toward the tube bundle shroud 3. The ends of the tube bundle shroud inner members 35 b opposite to the annular portions 35 a are attached to the tube bundle shroud 3 through the pedestals 35 d fixed to the inner wall surface of the tube bundle shroud 3. The tube bundle shroud inner members 35 b and the pedestals 35 d are attached to each other by, for example, welding. Further, the pedestals 35 d are fixed to the tube bundle shroud 3 by, for example, a fastening member such as a bolt. Each tube bundle shroud inner member 35 b may be a hollow circular tube or a solid bar-like body.

As illustrated in FIGS. 21 to 23, the tube bundle shroud outer members 35 c are interposed between the tube bundle shroud 3 and the cylinder portion 2 at the outside of the tube bundle shroud 3 so as to support the respective tube bundle shroud inner members 35 b. The tube bundle shroud outer members 35 c are provided so as to be continuous to the outside of the respective tube bundle shroud inner members 35 b through the tube bundle shroud 3, and are formed as bar-like bodies connecting the tube bundle shroud 3 and the cylinder portion 2 to each other. In each tube bundle shroud outer member 35 c, one end thereof is attached to the tube bundle shroud 3 through the pedestal 35 d fixed to the outer wall surface of the tube bundle shroud 3, and the other end thereof is attached to the cylinder portion 2 through the pedestal 35 d fixed to the inner wall surface of the cylinder portion 2. The tube bundle shroud outer member 35 c and the pedestal 35 d are attached to each other by, for example, welding. Further, the pedestal 35 d is fixed to the tube bundle shroud 3 or the cylinder portion 2 by, for example, a fastening member such as a bolt. The tube bundle shroud outer member 35 c may be a hollow circular tube or a solid bar-like body.

That is, the annular portions 35 a are supported to the cylinder portion 2 and the tube bundle shroud 3 by the tube bundle shroud inner members 35 b and the tube bundle shroud outer members 35 c. Then, the supported annular portions 35 a are arranged at a predetermined interval so as not to contact the U-bent portion 18 and the tube bundle shroud 3.

The partition plate 30 is supported to the support portion 35.s illustrated in FIG. 21, the partition plate 30 is supported to a support member 35 e extending from the annular portion 35 a. Furthermore, it is desirable to support the partition plate 30 by a plurality of (here, two) annular portions 35 a when ensuring the support force.

In this way, since the partition plate 30 is supported by the support portion 35, the partition plate 30 may be supported to the cylinder portion 2 by being inserted between the heat transfer tubes 5 of the U-bent portion 18. Furthermore, in a case where the support portion 35 is used, the partition plate 30 may be separated from the tube support plate 6 if necessary.

FIG. 24 is a side view illustrating another embodiment of the support portion of the steam generator according to the second embodiment.

As illustrated in FIG. 24, a support portion 36 includes tube bundle shroud outer members 36 a. The tube bundle shroud outer members 36 a are provided between the tube bundle shroud 3 and the cylinder portion 2 at the outside of the tube bundle shroud 3. The tube bundle shroud outer member 36 a is provided so as to be continuous to the end of the partition plate 30 extending to the tube bundle shroud 3 through the tube bundle shroud 3, and is formed as a bar-like body connecting the tube bundle shroud 3 and the cylinder portion 2 to each other. In the tube bundle shroud outer member 36 a, one end thereof is attached to the tube bundle shroud 3 through a pedestal 36 b fixed to the outer wall surface of the tube bundle shroud 3, and the other end thereof is attached to the cylinder portion 2 through the pedestal 36 b fixed to the inner wall surface of the cylinder portion 2. The tube bundle shroud outer member 36 a and the pedestal 36 b are attached to each other by, for example, welding. Further, the pedestal 36 b is fixed to the tube bundle shroud 3 or the cylinder portion 2 by, for example, a fastening member such as a bolt. The tube bundle shroud outer member 36 a may be a hollow circular tube or a solid bar-like body.

The partition plate 30 is supported to the support portion 36. The partition plate 30 is supported by the tube bundle shroud 3 through the pedestal 3 b fixed to the inner wall surface of the tube bundle shroud 3 so that the end thereof extends to the tube bundle shroud 3 so as to be continuous to the inside of the tube bundle shroud outer member 36 a. Furthermore, it is desirable to support the end of the partition plate 30 by a plurality of (here, three) tube bundle shroud outer members 36 a when ensuring the support force.

In this way, since the partition plate 30 is supported by the support portion 36, the partition plate 30 may be supported to the cylinder portion 2 by being inserted between the heat transfer tubes 5 of the U-bent portion 18. Furthermore, in a case where the support portion 36 is used, the partition plate 30 may be separated from to tube support plate 6 if necessary.

FIG. 25 is a side view illustrating another embodiment of the support portion of the steam generator according to the second embodiment.

As illustrated in FIG. 25, a support portion 37 includes tube bundle shroud inner members 37 a and tube bundle shroud outer members 37 b.

The tube bundle shroud inner members 37 a are provided between the plate surface of the partition plate 30 and the tube bundle shroud 3 at the inside of the tube bundle shroud 3. The tube bundle shroud inner members 37 a are formed as bar-like bodies extending toward the inner wall surface at the center of the tube bundle shroud 3. The ends of the tube bundle shroud inner members 37 a near the tube bundle shroud 3 are attached to the tube bundle shroud 3 through pedestals 37 c fixed to the inner wall surface of the tube bundle shroud 3. The tube bundle shroud inner member 36 a and the pedestal 36 b are attached to each other by, for example, welding. Further, the pedestal 36 b is fixed to the tube bundle shroud 3 by, for example, a fastening member such as a bolt. The tube bundle shroud inner member 37 a may be a hollow circular tube or a solid bar-like body.

The tube bundle shroud outer members 37 b are interposed between the tube bundle shroud 3 and the cylinder portion 2 at the outside of the tube bundle shroud 3 so as to support the respective tube bundle shroud inner members 37 a. The tube bundle shroud outer members 37 b are provided so as to be continuous to the outside of the respective tube bundle shroud inner members 37 a through the tube bundle shroud 3, and are formed as bar-like bodies connecting the tube bundle shroud 3 and the cylinder portion 2 to each other. In the tube bundle shroud outer member 37 b, one end thereof is attached to the tube bundle shroud 3 through the pedestal 37 c fixed to the outer wall surface of the tube bundle shroud 3, and the other end thereof is attached to the cylinder portion 2 through the pedestal 37 c fixed to the inner wall surface of the cylinder portion 2. The tube bundle shroud outer member 37 b and the pedestal 37 c are attached to each other by, for example, welding. Further, the pedestal 37 c is fixed to the tube bundle shroud 3 or the cylinder portion 2 by, for example, a fastening member such as a bolt. The tube bundle shroud outer member 37 b may be a hollow circular-tube or a solid bar-like body.

The partition plate 30 is supported to the support portion 37. The partition plate 30 is supported to the tube bundle shroud inner member 37 a through the pedestal 37 c so as to be sandwiched between the respective tube bundle shroud inner members 37 a extending toward both plate surfaces. Furthermore, it is desirable to support the partition plate 30 by sandwiching both plate surfaces thereof at a plurality of positions (here, six positions in total by three positions for each end side of the partition plate 30) by the tube bundle shroud inner members 37 a when ensuring the support force.

In this way, since the partition plate 30 is supported by the support portion 36, the partition plate 30 may be supported to the cylinder portion 2 by being inserted between the heat transfer tubes 5 of the U-bent portion 18. Furthermore, in a case where the support portion 37 is used, the partition plate 30 may be separated from the tube support plate 6 if necessary.

FIG. 26 is a schematic diagram illustrating a bonding mechanism of the steam generator according to the second embodiment.

As illustrated in FIG. 26, in the steam generator 1 of the embodiment, a bonding mechanism 38 is provided between each of the support portions 35, 35, and 37 and the partition plate 30 or between the members of the support portions 35, 36, and 37 so as to bond them to each other with a predetermined gap E therebetween.

In FIG. 26, the bonding mechanism 33 is provided between the partition plate 30 and the support member 35 e of the support portion 35, between the partition plate 30 and the pedestal 36 b at the inside of the tube bundle shroud 3 of the support portion 3, or between the partition plate 30 and the pedestal 37 c of the support portion 37 near the partition plate 30 so as to bond them to each other with the gap E so that the partition plate 30 is interposed therebetween.

Further, although not illustrated in the drawings, the bonding mechanism 38 may be provided between the support member 35 e and the annular portion 35 a of the support portion 35, between the annular portion 35 a and the tube bundle shroud inner member 35 b, between the tube bundle shroud inner member 35 b and the pedestal 35 d at the inside of the tube bundle shroud 3, the tube bundle shroud outer member 35 c and the pedestal 35 d at the outside of the tube bundle shroud 3, or the tube bundle shroud outer member 35 c and the pedestal 35 d near the cylinder portion 2.

Further, although not illustrated in the drawings, the bonding mechanism 38 may be provided between the tube bundle shroud outer member 36 a and the pedestal 3 b at the outside of the tube bundle shroud 3 of the support portion 36 or between the tube bundle, shroud outer member 36 a and the pedestal 36 b near the cylinder portion 2.

Further, although not illustrated in the drawings, the bonding mechanism 36 may be provided between the tube bundle shroud inner member 37 a and the pedestal 37 c near the partition plate 30 of the support portion 37, between the tube bundle shroud inner member 37 a and the pedestal 37 c at the inside of the tube bundle shroud 3, between the tube bundle shroud outer member 37 b and the pedestal 37 c at the outside of the tube bundle shroud 3, or between the tube bundle shroud outer member 37 b and the pedestal 37 c near the cylinder portion 2.

In this way, since the bonding mechanism 38 is provided between each of the support portions 35, 36, and 37 and the partition plate 30 or the members of the support portions 35, 36, and 37 so as to bond them to each other with the predetermined gap E therebetween, the members are not strongly fixed to each other by the bonding mechanism 38. For this reason, it is possible to prevent the vibration during the general operation of the steam generator 1 from being transmitted to the cylinder portion 2 or the partition plate 30.

FIG. 27 is a schematic diagram illustrating a damping mechanism of the steam generator according to the second embodiment.

As illustrated in FIG. 27, in the steam generator 1 of the embodiment, a damping mechanism 39 is provided between each of the support portions 35, 36, and 37 and the partition plate 30 or between the members of the support portions 35, 36, and 37 so as to connect them to each other and damps the relative movement thereof while allowing the movement.

In FIG. 27, the damping mechanism 39 is provided between the partition plate 30 and the support member 35 e of the support portion 35, between the partition plate 30 and the pedestal 36 b at the inside of the tube bundle shroud 3 of the support portion 36, or between the partition plate 30 and the pedestal 37 c near the partition plate 30 of the support portion 37 so as to damp the relative movement thereof while allowing the movement.

For example, in the damping mechanism 39, one side (the partition plate 30 in FIG. 27) is connected to a piston rod 39 b provided with a piston 39 a and one side (the support member 35 e, the pedestal 36 b, and the pedestal 37 c in FIG. 27) is connected to an outer cylinder 39 c accommodating the piston 39 a. The outer cylinder 39 c is provided so that a free piston 39 d forms a gas chamber 39 e therein. Further, a fluid (for example, water) like the secondary cooling water inside the steam generator 1 is stored in a portion where the piston 39 a moves in a region other than the gas chamber 39 e inside the outer cylinder 39 c. Furthermore, in FIG. 27, the damping mechanisms 39 are provided at both sides of the partition plate 30, but the damping mechanism 39 may be provided only at one side thereof.

Further, although not illustrated in the drawings, the damping mechanism 39 may be provided between the support member 35 e and the annular portion 35 a of the support portion 35, between the annular portion 35 a and the tube bundle shroud inner member 35 b, between the tube bundle shroud inner member 35 b and the pedestal 35 d at the inside of the tube bundle shroud 3, between the tube bundle shroud outer member 35 c and the pedestal 35 d at the outside of the tube bundle shroud 3, or between the tube bundle shroud outer member 35 c and the pedestal 35 d near the cylinder portion 2.

Further, although not illustrated in the drawings, the damping mechanism 39 may be provided between the tube bundle shroud outer member 36 a and the pedestal 36 b at the outside of the tube bundle shroud 3 in the support portion 36 or between the tube bundle shroud outer member 36 a and the pedestal 3 b near the cylinder portion 2.

Further, although not illustrated in the drawings, the damping mechanism 39 may be provided between the tube bundle shroud inner member 37 a and the pedestal 37 c near the partition plate 30 in the support portion 37, between the tube bundle shroud inner member 37 a and the pedestal 37 c at the inside of the tube bundle shroud 3, between the tube bundle shroud outer member 37 b and the pedestal 37 c at the outside of the tube bundle shroud 3, or between the tube bundle shroud outer member 37 b and the pedestal 37 c near the cylinder portion 2.

In this way, since the oscillation generated between each of the support portions 35, 36, and 37 and the partition plate 30 or between the members of the support portions 35, 36, and 37 is damped by the damping mechanism 39, the quake resistance of the U-bent portion may be further ensured.

FIG. 28 is a schematic diagram illustrating another embodiment of the damping mechanism of the steam generator according to the second embodiment.

In the steam generator 1 of the embodiment, a damping mechanism 40 is provided between each of the support portions 35, 36, and 37 and the partition plate 30 or between the members of the support portions 35, 36, and 37 so as to connect them to each other and damps the relative movement thereof while allowing the movement.

In the damping mechanism 40, one (the partition plate 30 in FIG. 28) of the support portions 35, 36, and 37 and the partition plate 30 is sandwiched between the other members (the support member 35 e, the pedestal 36 b, and the pedestal 37 c in FIG. 28), and a friction generating portion 40 a is provided between the relative surfaces thereof. As the friction generating portion 40 a, it is desirable to employ a friction generating portion which applies a frictional force for damping the oscillation between the relative surfaces when deflection occurs. Further, a sandwiching force may be adjusted by a fastening force of a bolt so as to adjust the frictional force between the relative surfaces. Furthermore, in FIG. 28, the support members 35 e, the pedestals 36 b, and the pedestals 37 c are provided at both sides of the partition plate 30, but these members may be arranged at the opposite positions.

Further, although not illustrated in the drawings, the damping mechanism 40 may be provided between the support member 35 e and the annular portion 35 a of the support portion 35, between the annular portion 35 a and the tube bundle shroud inner member 35 b, between the tube bundle shroud inner member 35 b and the pedestal 35 d at the inside of the tube bundle shroud 3, between the tube bundle shroud outer member 35 c and the pedestal 35 d at the outside of the tube bundle shroud 3, or between the tube bundle shroud outer member 35 c and the pedestal 35 d near the cylinder portion 2.

Further, although not illustrated in the drawings, the damping mechanism 40 may be provided between the tube bundle shroud outer member 36 a and the pedestal 3 b at the outside of the tube bundle shroud 3 of the support portion 36 or between the tube bundle shroud outer member 36 a and the pedestal 35 b near the cylinder portion 2.

Further, although not illustrated in the drawings, the damping mechanism 40 may be provided between the tube bundle shroud inner member 37 a and the pedestal 37 c near the partition plate 30 of the support portion 37, between the tube bundle shroud inner member 37 a and the pedestal 37 c at the inside of the tube bundle shroud 3, between the tube bundle shroud outer member 37 b and the pedestal 37 c at the outside of the tube bundle shroud 3, or between the tube bundle shroud outer member 37 b and the pedestal 37 c near the cylinder portion 2.

In this way, since the oscillation generated between each of the support portions 35, 35, and 37 and the partition plate 30 or between the members of the support portions 35, 36, and 37 is damped by the damping mechanism 40, the quake resistance of the U-bent portion 18 may be further ensured.

Third Embodiment

FIG. 29 is a perspective view illustrating a U-bent portion of a steam generator according to a third embodiment. FIG. 30 is a longitudinal sectional view illustrating a relation of a vibration preventing member, a holding member, and a bridge in the out-of-plane direction of the steam generator according to the third embodiment. FIG. 31 is a plan view illustrating a quake-resistant structure of the steam generator according to the third embodiment. FIG. 32 is a longitudinal sectional view illustrating the quake-resistant structure of the steam generator according to the third embodiment. FIG. 33 is a longitudinal sectional view illustrating a relation of a bridge and a regulation member in the out-of-plane direction of the quake-resistant structure of the steam generator according to the third embodiment.

As illustrated in FIGS. 29 to 32, the quake-resistant structure (hereinafter, referred to as the quake-resistant structure) of the steam generator 1 of the embodiment includes a beam member 81 that is disposed at the top portion side (the upper side) of the U-bent portion 18, an outer tube support member 83 that connects the tube bundle shroud 3 and the cylinder portion 2 to each other, and a movement regulation portion 90 that regulates the relative m of the U-bent portion 18 with respect to the beam member 81.

The beam member 81 is disposed at the top portion side of the U-bent portion 18 with a gap with respect to the U-bent portion. The beam member 81 is formed in a bar shape which extends in the out-of-plane direction D1 of the U-bent portion 18, and both ends thereof are respectively fixed to the inner peripheral surface of the tube bundle shroud 3. Further, in the beam member 81, a portion excluding both ends thereof in the extension direction is curved along the semi-spherical surface of the U-bent portion 18. Accordingly, the portion is disposed so as to face the semi-spherical surface of the U-bent portion 18 with a constant gap therebetween. The beam member 81 of the embodiment is formed as, for example, a single steel member.

A plurality of (here, three) beam members 81 are provided with a gap therebetween in the in-plane direction D2, that is, the horizontal direction following the plane including the bent portion 5U of the heat transfer tube 5 of the U-bent portion 18. In other words, a plurality of (here, three) beam members 81 are provided with a gap therebetween in the extension direction of the bent portion 5U. Furthermore, it is desirable that the cross-sectional shape of the beam member 81 in a direction perpendicular to the extension direction have, for example, a vane shape so as to reduce the flow resistance of the fluid around the beam member 81.

As illustrated in FIGS. 31 and 32, a plurality of the outer tube support member 83 are disposed throughout the outer peripheral surface of the tube bundle shroud 3 and the inner peripheral surface of the cylinder portion 2, and are provided with a gap therebetween in the circumferential direction of the tube bundle shroud 3 and the cylinder portion 2. Each outer tube support member 83 includes a bar portion 84 which extends in the radial direction of the tube bundle shroud 3 and the cylinder portion 2 and an inner pedestal 85 and an outer pedestal 86 which are fixed to both ends of the bar portion 84.

The inner pedestal 85 is integrally fixed to the inner end of the bar portion 84 in the radial direction of the tube bundle shroud 3 and the cylinder portion 2 by, for example, welding or the like, and is fixed to the outer peripheral surface of the tube bundle shroud 3 by, for example, a fastening member such as a bolt. The outer pedestal 36 is integrally fixed to the outer end of the bar portion 84 in the radial direction of the tube bundle shroud 3 and the cylinder portion 2 by, for example, welding or the like as in the inner pedestal 85, and is fixed to the inner peripheral surface of the cylinder portion 2 by, for example, a fastening member such as a bolt. With such a structure, the outer tube support member 83 connects the cylinder portion 2 and the tube bundle shroud 3 to each other.

The movement regulation portion 90 includes the vibration preventing member 14, the holding member 16, and the bridge 17 and further includes a regulation member 91.

As illustrated in FIGS. 29, 30, 32, and 33, a plurality of regulation members 91 are fixed to the surface of the beam member 81 facing the inner side of the semi-spherical U-bent portion 18 in the radial direction, and are provided with a gap therebetween in the extension direction of the beam member 81. The regulation members 91 are provided so as to make a pair with the plurality of bridges 17. That is, the regulation members 91 are provided at positions corresponding to the plurality of bridges 17 which are disposed with a gap therebetween in the out-of-plane direction D1.

Each regulation member 91 regulates the movement of the bridge 17 in the out-of-plane direction D1 by sandwiching the bridge 17, connecting the bonding members 15 as the ends of the plurality of vibration preventing members 14 disposed between the heat transfer tubes 5 of the U-bent portion 18, with a predetermined gap therebetween in the out-of-plane direction D1. The regulation member 91 includes a groove portion 92 which is recessed toward the outside in the radial direction at the surface of the regulation member 91 facing the inside of the semi-spherical U-bent portion 18 in the radial direction. The bridge 17 is sandwiched in the groove portion 92 with a predetermined gap therebetween. The regulation member 91 is bonded by a bonding method, for example, welding or the like. Since the regulation member 91 and the bridge 17 have a predetermined gap (for example, about 5 mm to 10 mm) in the out-of-plane direction D1, a gap is formed therebetween.

According to the steam generator 1 with the above-described configuration, when an earthquake or the like is generated, an earthquake acceleration is applied to the U-bent portion 18 in the out-of-plane direction D1, and the U-bent portion 18 is vibrated, the vibration of the U-bent portion 18 in the out-of-plane direction D1 may be received by the beam member 81 that extends along the semi-spherical surface of the U-bent portion 18 in the out-of-plane direction D1. That is, since the beam member 81 may suppress the vibration by receiving the vibration of the U-bent portion 18 when the U-bent portion 18 is vibrated in the out-of-plane direction D1 more than the range of the gap between the beam member 81 and the semi-spherical surface of the U-bent portion 18, the quake resistance of the U-bent portion 18 may be ensured.

Further, since the beam member 81 is disposed with a gap respect to the U-bent portion 18 as described above, the restraining force of the U-bent portion 18 may be reduced. Particularly, in this embodiment, since the beam member 81 does not restrain the heat transfer tube 5 of the U-bent portion 18, the restraining force is not generated. For this reason, when the steam generator 1 is operated, it is possible to suppress the vibration abrasion or the like of the heat transfer tube 5 or the like caused by the secondary cooling water passing between the beam member 81 and the U-bent portion 18. As a result, the quake-resistant structure using the beam member 81 may reduce an influence on the resistance with respect to the flow oscillation of the heat transfer tube 5 and ensure the resistance. Further, since the beam member 81 may be attached to even the existing steam generator 1 by a repairing work, the quake-resistant structure may improve the quake resistance of the existing steam generator 1.

Here, since the primary cooling water which exchanges heat with the secondary cooling water circulates inside the heat transfer tube 5, a difference in temperature occurs between one side of the bent portion 5U of the heat transfer tube 5 in the in-plane direction D2 and the other side thereof in the in-plane direction D2. That is, the temperature of the primary cooling water at the upstream side of the bent portion 5U (the U-bent portion 18) becomes higher than that of the downstream side. Thus, when the beam member 81 is disposed so as to extend in the in-plane direction D2 along the semi-spherical surface of the U-bent portion 18, a difference in temperature also occurs in the beam member 81 in the extension direction thereof due to the influence of the heat transmitted from the bent portion 5U. Thus, since a thermal expansion biased in the extension direction occurs in the beam member 81, the gap between the beam member 81 and the U-bent portion 18 may not be maintained uniformly. Accordingly, there is a concern that the quake resistance of the U-bent portion 18 may not be ensured by the beam member 81.

On the contrary, in this embodiment, since the beam member 81 extends in the out-of-plane direction D1 along the semi-spherical surface of the U-bent portion 18, a difference in temperature does not occur in the beam member 81 in the extension direction thereof. That is, since the temperature of the U-bent portion 18 is uniform in the extension direction of the beam member 81, that is, the out-of-Jane direction D1, the heat is also uniformly transmitted from the U-bent portion 18 to the beam member 81 in the out-of-plane direction D1. Thus, since the thermal expansion of the beam member 81 is not biased in the extension direction, the gap between the beam member 81 and the U-bent portion 18 may be uniformly maintained. Accordingly, the quake resistance of the U-bent portion 18 may be reliably ensured by the beam member 81.

Further, since the steam generator 1 of the embodiment includes the movement regulation portion 90 which regulates the relative movement of the U-bent portion 18 with respect to the beam member 81 in the out-of-plane direction D1, the vibration of the U-bent portion 18 may be reliably suppressed by the beam member 81 in the event of an earthquake, and hence the restraining force of the U-bent portion 18 may be reduced during the operation of the steam generator 1.

That is, since the regulation member 91 attached to the beam member 81 does not restrain the heat transfer tube 5 which is supported by the bridge 17 through the vibration preventing member 14 in the U-bent portion 18, a restraining force with respect to the heat transfer tube 5 is not generated. For this reason, when the steam generator 1 is operated, the vibration abrasion or the like of the bridge 17 caused by the secondary cooling water passing through the gap formed between the regulation member 91 and the U-bent portion 18 may be suppressed. Thus, it is possible to reduce an influence on the resistance with respect to the flow oscillation of the heat transfer tube 5 and hence to suppress degradation in the resistance.

Further, when the U-bent portion 18 and the bridge 17 are vibrated in the oat-of-plane direction D1 due to an earthquake or the like, the regulation member 91 integrated with the beam member 81 regulates the vibration of the bridge 17. Since the bridge 17 supports the plurality of heat transfer tubes 5 of the U-bent portion 18, such a vibration is also regulated by the regulation member 91. Furthermore, when the gap between the regulation member 91 and the bridge 17 is set to be smaller than the gap between the beam member 81 and the plurality of heat transfer tubes 5 of the U-bent portion 18, the vibration of the U-bent portion 18 in the out-of-plane direction D1 may be further effectively suppressed. As a result, the quake-resistant structure with the regulation member 91 may further reliably ensure the quake resistance of the U-bent portion 18.

Further, in this embodiment, since the outer tube support member 83 is provided so as to connect the tube bundle shroud 3 and the cylinder portion 2 to each other, the vibration of the U-bent portion 18 in the out-of-plane direction D1 may be received by the cylinder portion 2 through the beam member 81, the tube bundle shroud 3, and the outer tube support member 83. Accordingly, the quake resistance of the U-bent portion 18 may be reliably obtained.

Moreover, since the plurality of beam members 81 are provided with a gap therebetween in the extension direction of the bent portion 5U, that is, the in-plane direction D2, the vibration of the U-bent portion 18 may be further reliably suppressed and the quake resistance may be further ensured.

FIG. 34 is a longitudinal sectional view illustrating another embodiment of the quake-resistant structure of the steam generator according to the third embodiment. FIG. 35 is a longitudinal sectional view illustrating a connection position of the divided beams of the embodiment illustrated in FIG. 34. FIG. 36 is a cross-sectional view illustrating a connection portion of the divided beams of the embodiment illustrated in FIG. 34. Furthermore, in another embodiment, the same sign will be given to the same component as that of the above-described embodiment, and the description thereof will not be repeated.

As illustrated in FIG. 34, the beam member 101 is different from the beam member 81 of the above-described embodiment in that the beam member 101 is obtained by connecting a plurality of divided beams 102. That is, as illustrated in FIGS. 34 to 36, the beam member 101 includes the plurality of (here, six) divided beams 102 and a connection pin 105 connecting the adjacent divided beams 102 to each other.

The divided beams 102 are formed in a shape in which the beam member 101 is divided into a plurality of portions in the extension direction thereof, and the beam member 101 is formed by sequentially connecting the divided beams 102. As illustrated in FIGS. 35 and 36, one end of each of the divided beams 102 is provided with a convex portion 103 which protrudes from the one end, and the other end of each of the divided beams 102 is provided with a concave portion 104 which is recessed from the other end and is fittable to the convex portion 103. Then, the divided beams 102 are connected to each other in a manner such that the convex portion 103 and the concave portion 104 are connected to each other while being fitted to each other by the connection pin 105.

The connection pin 105 includes a pin body 106 that penetrates the convex portion 103 and the concave portion 104 which are fitted to each other at the adjacent position and a welded portion 107 that is formed at both ends of the pin body 106. That is, the connection pin 105 prevents the separation of the pin body 106 from the convex portion 103 and the concave portion 104 by forming the welded portion 107 through the buildup welding of both ends of the pin body 106 while the pin body 106 penetrates the convex portion 103 and the concave portion 104 so as to connect both each other. In this embodiment, the divided beam 102 are connected to each other by two connection pins 105, but may be connected to each other by one connection pin or three or more connection pins.

Here, generally, various structures are provided at the top portion side of the U-bent portion 18 in the steam generator 1. For this reason, it is difficult to carry and install the beam member 81 as a single member to the installation position of the existing steam generator 1. On the contrary, since the beam member 101 includes the plurality of divided beams 102 and the divided beams 102 are connected to each other at the installation position of the beam member 101, the beam member 101 may be easily installed. Furthermore, the invention is not limited to the connection using the connection pin 105, and the divided beams 102 may be connected to each other by welding or the like.

FIG. 37 is a longitudinal sectional view illustrating another embodiment of the quake-resistant structure of the steam generator according to the third embodiment. Furthermore, in another embodiment, the same sign will be given to the same component as that of the above-described embodiment, and the description thereof will not be repeated.

As illustrated in FIG. 37, since a beam member 108 forms a truss structure, the beam member is different from the beam members 81 and 101 of the above-described embodiments.

That is, as illustrated in FIG. 37, the beam member 100 is formed by handing bar members 109 through a pin. Accordingly, it is possible to decrease the cross-sectional area perpendicular to the extension direction of the beam member 108 while ensuring the rigidity of the beam member 105. Thus, it is possible to obtain a function of suppressing the vibration of the U-bent portion 18 in the out-of-plane direction. D1 by the beam member 100 without degrading the performance of the steam generator 1.

While the third embodiment of the invention has been described in detail, the invention is not limited to the embodiment, and a slight modification in design ma be also made without departing from the technical spirit of the invention. For example, the number of the beam members 81, 101, and 108 is not limited to three, and may be two or four or more. Further, when the quake resistance of the U-bent portion 18 may be ensured only by one beam member 81, 101, or 108, the number of the beam members 81, 101, and 108 may be one.

Further, in the third embodiment, an example has been described in which the beam members 81, 101, and 108 extending in the out-of-plane direction D1 are provided, but the invention is not limited thereto. For example, the second beam member may be provided so as to extend in the in-plane direction D2 or obliquely extend in the out-of-plane direction D1 and the in-plane direction D2. Accordingly, the quake-resistant strength of the U-bent portion 18 may be further improved.

Furthermore, the beam members 81, 101, and 108 of the third embodiment correspond to a configuration in which the first support member and the second support member of the first embodiment are included, and the outer tube support member 83 of the third embodiment corresponds to the third support member of the first embodiment. Further, the regulation member 91 of the third embodiment corresponds to the regulation member of the first embodiment, and the modified example thereof may be adopted.

REFERENCE SIGNS LIST

-   -   1 STEAM GENERATOR     -   2 CYLINDER PORTION     -   3 TUBE BUNDLE SHROUD     -   4 TUBE SHEET     -   5 HEAT TRANSFER TUBE     -   5A HEAT TRANSFER TUBE LAYER     -   5U BENT PORTION     -   6 TUBE SUPPORT PLATE (SUPPORT PORTION)     -   7 CHANNEL HEAD     -   8 PARTITION WALL     -   9 STEAM-WATER SEPARATOR     -   10 MOISTURE SEPARATOR     -   11 WATER FEEDING TUBE     -   12 STEAM DISCHARGE. PORT     -   13 WATER FEEDING LINE     -   14 VIBRATION PREVENTING MEMBER     -   16 HOLDING MEMBER.     -   17, 17 a, 17 c. BRIDGE     -   17Ta, 17Tc. BRIDGE END     -   17S, 17Sa SIDE SURFACE     -   18 U-BENT PORTION     -   18T TOP PORTION     -   20, 20 a QUAKE-RESISTANT STRUCTURE     -   21, 21A, 21B, 21 a. ANNULAR. MEMBER (FIRST SUPPORT MEMBER)     -   22, 22A, 22B, 22 a. SECOND SUPPORT MEMBER     -   23, 23A, 23B, 23 a. THIRD SUPPORT MEMBER     -   24, 24A, 24B, 24 a. REGULATION MEMBER     -   24E EXTENSION PORTION     -   24Y OUTER PORTION     -   24E GROOVE PORTION     -   25 ORIFICE     -   26, 26 c INTERMEDIATE: SUPPORT MEMBER     -   27 PEDESTAL     -   30 PARTITION PLATE     -   30 a PARTITION PLATE     -   31 PENETRATION HOLE     -   35 SUPPORT PORTION     -   35 a ANNULAR PORTION     -   35 b TUBE BUNDLE SHROUD INNER MEMBER     -   35 c. TUBE BUNDLE SHROUD OUTER MEMBER     -   35 d PEDESTAL     -   35 e SUPPORT MEMBER     -   36 SUPPORT PORTION     -   36 a TUBE BUNDLE SHROUD OUTER MEMBER     -   36 b PEDESTAL     -   37 SUPPORT PORTION     -   37 a TUBE BUNDLE SHROUD INNER MEMBER     -   37 b TUBE BUNDLE SHROUD OUTER MEMBER     -   37 c PEDESTAL     -   38 BONDING MECHANISM     -   39 DAMPING MECHANISM     -   40 DAMPING MECHANISM     -   E GAP     -   81 BEAM MEMBER     -   83 OUTER. TUBE SUPPORT MEMBER     -   84 BAR. PORTION     -   85 INNER. PEDESTAL     -   86 OUTER. PEDESTAL     -   90 MOVEMENT REGULATION PORTION     -   101 BEAM MEMBER     -   108 BEAM MEMBER 

1. A steam generator comprising: a first support member that surrounds a U-bent portion obtained by collectively disposing bent portions of a plurality of heat transfer tubes and is provided between the U-bent portion and a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion so as to have a predetermined gap with respect to the U-bent portion; a second support member that is provided between the first support member and the tube bundle shroud; and a third support member that is attached to a cylinder portion accommodating the plurality of heat transfer tubes and supports the second support member.
 2. The steam generator according to claim 1, wherein the first support member includes a regulation member that sandwiches a bridge, connecting a plurality of holding members connecting ends of a plurality of vibration preventing members disposed between the heat transfer tubes in the portion, with a predetermined gap therebetween so as to regulate a movement of the bridge.
 3. The steam generator according to claim 2, wherein the regulation member includes an orifice that is formed at a portion facing the bridge.
 4. The steam generator according to claim 1, wherein a plurality of the second support members extend radially from the first support member toward the tube bundle shroud and are fixed to the tube bundle shroud, and a plurality of the third support members extend radially from the tube bundle shroud and connect the tube bundle shroud and the cylinder portion to each other.
 5. The steam generator according to claim 1, wherein a plurality of the first support members are disposed toward a top portion of the U-bent portion.
 6. The steam generator according to claim 5, wherein the plurality of second support members overlap each other and the plurality of second members overlap each other between the plurality of the plurality of first support members when viewed from a direction in which the plurality of first support members are arranged.
 7. A steam generator with a U-bent portion obtained by collectively disposing circular-arc portions of upper ends of a plurality of inverse U-shaped heat transfer tubes, the steam generator comprising: partition plates that are inserted between the heat transfer tubes of the U-bent portion so as to divide the U-bent portion into a plurality of portions and are supported by a support portion to a cylinder portion accommodating the heat transfer tubes of the steam generator.
 8. The steam generator according to claim 7, wherein the partition plates are provided at a plurality of positions.
 9. The steam generator according to claim 7, wherein the partition plates are provided so as to overlap each other.
 10. The steam generator according to claim 7, wherein the partition plates are provided with a penetration hole.
 11. The steam generator according to claim 10, wherein the penetration hole is formed as an orifice.
 12. The steam generator according to claim 7, wherein the support portion is a tube support plate that is supported to the cylinder portion so as to fix the heat transfer tubes.
 13. The steam generator according to claim 7, wherein the support portion includes an annular portion that surrounds the U-bent portion at the inside of a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion, a tube bundle shroud inner member that is interposed between the tube bundle shroud and the annular portion at the inside of the tube bundle shroud and supports the annular portion, and a tube bundle shroud outer member that is interposed between the tube bundle shroud and the cylinder portion at the outside of the tube bundle shroud and supports the tube bundle shroud inner member, and the partition plate is supported by the annular portion.
 14. The steam generator according to claim 7, wherein the support portion includes a tube bundle shroud outer member that is interposed between the tube bundle shroud and the cylinder portion at the outside of a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion, and an end of the partition plate extending to the tube bundle shroud is supported by the tube bundle shroud outer member.
 15. The steam generator according to claim 7, wherein the support portion includes a tube bundle shroud inner member that is provided at the inside of a tube bundle shroud surrounding an outer peripheral portion of the U-bent portion and a tube bundle shroud outer member that is interposed between the tube bundle shroud and the cylinder portion at the outside of the tube bundle shroud and supports the tube bundle shroud inner member, and the partition plate is supported so as to be sandwiched between the plurality of tube bundle Shroud inner members.
 16. The steam generator according to claim 7, wherein a bonding mechanism is provided between the support portion and the partition plate or between members of the support portion so as to bond them to each other with a predetermined gap therebetween.
 17. The steam generator according to claim 7, Wherein a damping mechanism is provided between the support portion and the partition plate or between members of the support portion so as to connect them to each other and damps a relative movement therebetween while allowing the movement.
 18. A steam generator comprising: a U-bent portion in which a plurality of bent portions of a plurality of heat transfer tubes are formed in a U-shape so as to form a semi-spherical shape on the whole and are disposed in the out-of-plane direction perpendicular to a plane including the bent portions; a tube bundle shroud that surrounds the U-bent portions at the outer peripheral side thereof and a beam member that is disposed near a top portion of the U-bent portion so as to have a gap with respect to the U-bent portion and has both ends fixed to an inner peripheral surface of the tube bundle shroud so that the beam member extends in the out-of-plane direction along a semi-spherical surface of the U-bent portion.
 19. The steam generator according to claim 18, further comprising: a movement regulation portion that regulates a relative movement of the U-bent portion with respect to the beam member in the out-of-plane direction.
 20. The steam generator according to claim 19, wherein the movement regulation portion includes a plurality of vibration preventing members that are disposed between the adjacent heat transfer tubes in the out-of-plane direction so as to connect the adjacent heat transfer tubes to each other and has an end protruding from the semi-spherical surface, a bridge that connects ends of the plurality of vibration preventing member to each other in the extension direction of the bent portion, and a regulation member that is provided in the beam member and sandwiches the bridge with a predetermined gap therebetween in the out-of-plane direction.
 21. The steam generator according to claim 18, further comprising: a cylinder portion that is provided at the outer peripheral side of the tube bundle shroud and accommodates the tube bundle shroud and the plurality of heat transfer tubes; and an outer tube support member that is disposed throughout an inner peripheral surface of the cylinder portion and an outer peripheral surface of the tube bundle shroud and supports the tube bundle shroud.
 22. The steam generator according to claim 18, wherein a plurality of the beam members are provided with a gap therebetween in the extension direction of the bent portion.
 23. The steam generator according to claim 18, wherein each beam member is obtained by connecting a plurality of divided beams in the out-of-plane direction.
 24. The steam generator according to claim 18, wherein the beam member forms a truss structure. 